Photoexcitation<span> is the photoelectrochemical process of electron excitation by photon absorption, when the energy of the photon is too low to cause photoionization. The absorption of the photon takes place in accordance with Planck's quantum theory.</span>
The earth's atmosphere consists mainly of nitrogen and oxygen with smaller proportions of other gases such as carbon dioxide. The amount of carbon dioxide in the atmosphere is maintained through a balance between processes such as photosynthesis, respiration and combustion. However this balance is being affected by human activities which are polluting the atmosphere.
The proportion of these gases in the atmosphere is as follows: nitrogen is the most abundant at 78%, oxygen is next at 21%, while others include carbon dioxide at 0.037% and argon at 0.9 % .
Flatworms possess excretory organs known as nephridia. Specifically as annelids, flatworms possess a variant known as metanephridia.
Cell membrane would be corr3eect
